IN INCISONAL AND VENTRAL HERNIA SURGERY
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Nieuwe inzichten in buikwandchirurgie
P R O E F S C H R I F T
ter verkrijging van de graad van doctor aan de Erasmus Universiteit Rotterdam op gezag van de rector magnificus
Prof.dr. R.C.M.E. Engels
en volgens het besluit van het College voor Promoties. De openbare verdediging zal plaatsvinden op
vrijdag 6 juli 2018 om 11:30 uur
door
Anuradha Jairam geboren te Rotterdam
Promotor: Prof. dr. J.F. Lange Overige leden: Prof. dr. C.H.J. van Eijck
Prof. dr. S.E.R. Hovius Prof. dr. N.D. Bouvy Copromotor: Prof. dr. J. Jeekel
Chapter 1 General introduction, aim and thesis outline 9
PART 1. PREVENTION OF INCISIONAL HERNIA
Chapter 2 European Hernia Society guidelines on closure of abdominal wall
incisions
25
Chapter 3 Short-term results of a randomized controlled trial comparing primary
suture with primary glued mesh augmentation to prevent incisional hernia
65
Chapter 4 Prevention of incisional hernia with prophylactic onlay and sublay
mesh reinforcement versus primary suture only in midline laparotomies (PRIMA): 2-year follow-up of a multicenter, double-blind randomized controlled trial
85
Chapter 5 Prevention of incisional hernia after midline laparotomy with prophylactic
mesh reinforcement: a meta-analysis and trial sequential analysis
109
Chapter 6 Prevention of incisional hernias with biological mesh: a systematic review
of literature
131
PART 2. NEW TOOLS, TECHNIQUES AND MESHES IN VENTRAL HERNIA SURGERY
Chapter 7 Patient reported outcome measurements in the diagnosis of incisional
hernia: PROMID questionnaire, a pilot study
151
Chapter 8 The use of resorbable synthetic meshes for non-complex abdominal wall
hernia in a preclinical setting: a review of literature
163
Chapter 9 A Post-Market, Prospective, Multi-Center, Single-Arm Clinical
Investigation of Phasix™ Mesh for VHWG Grade 3 Midline Incisional Hernia Repair
185
Chapter 10 Characteristics of different mesh types for abdominal wall hernia repair in
an experimental model of peritonitis
Chapter 12 Correction of hernia umbilicalis under local anesthesia: a prospective cohort
245
PART 3. GENERAL DISCUSSION, FUTURE PERSPECTIVES, SUMMARY, AND APPENDICES
Chapter 13 General discussion and future perspectives 257
Chapter 14 Summary 275 Samenvatting 279 Chapter 15 Acknowledgements 287 List of publications 290 PhD portfolio 295 Curriculum vitae 297
C H A P T E R
1
1
INTRODUCTION
Ventral Hernia
History
Ever since human kind is able to stand in a vertical position, abdominal wall hernias exist. The abdominal wall was first described in 1500 BC by the Ebers Papyrus, which was found by Professor George Ebers in a tomb in Thebes. Incisional hernias were not mentioned, however, epigastric hernias were described. In the passage that was found, it is suggested that reduction of the hernia takes place when the patient lies down. The importance of closure of the abdominal wall is first described centuries later (first century AD), by Aulus Cornelius Celsus. Surgical closure was named ‘gastrorrhaphy’, which literally means ‘suturing of the abdomen’. A layered closure of the abdominal wall was described to prevent incisional hernia (IH). The abdominal wall was more in detail described by Galen, a Roman of Greek origin and one of the most important physicians of the Greek-Roman period. Galen was most probably aware of the risk of IHs, since he described how to prevent it: by paramedian incisions. The work of Galen form the basis of modern surgery (1).
Anatomy
The abdominal wall is defined by several landmarks: cranially by the xiphoid process of the sternum, craniolaterally by the costal margins, inferolaterally by the inguinal ligaments and caudally by the iliac crests and pubic bone of the pelvis in the midline. The abdominal wall muscles ensure essential movements such as respiration, urination, defecation, coughing and giving birth. In addition, the abdominal wall muscles stabilize the trunk for walking upright. The abdominal wall exists of a layered structure, with nine layers in total: skin, subcuteanous tissue, superficial fascia (of Scarpa), external oblique muscle, internal oblique muscle, transversus abdominis muscle, fascia transversalis, preperitoneal adipose and areolar tissue and peritoneum. The internal oblique muscle, external oblique muscle and transversus abdominis muscle are positioned laterally to the abdominal rectus muscle. The linea alba is the preferred location to access the abdominal cavity. This structure, which literally means ‘white line’, is an avascular fibrous structure composed of collagen and elastin. It derives from the xiphoid process, extending to the pubis symphysis. The linea alba is the most important structure, since restoration of it remains the goal of abdominal wall reconstruction. It manifests a highly complex structure, consisting of three layers of collagen fibers in the same direction compared to the three lateral abdominal wall muscles. Closure can be achieved by approximating the paired rectus muscles back to the midline. The superior and inferior epigastric arteries are responsible for blood supply to the rectus muscles, originating
from the internal thoracic artery and external iliac artery. The epigastric arteries are situated between the abdominal rectus muscle and the posterior rectus fascia. The intercostal nerves innervate the rectus muscles.
Definition and classification
Incisional hernia is defined as: ‘any abdominal wall gap with or without a bulge in the
area of a postoperative scar perceptible or palpable by clinical examination or imaging’
(2). Primary abdominal wall hernias, or IHs, can be classified in midline and lateral abdominal wall hernias. Borders of a midline hernia are: the xyphoid (cranial), the pubic bone (caudal) and the lateral margin of the rectal sheath (lateral). Epigastric and umbilical hernias can be considered midline hernias. The borders of a lateral hernia are as follows: the costal margin (cranial) and the inguinal region (caudal). Spigelian and lumbar hernias are lateral hernias. An umbilical hernia is defined as ‘a midline abdominal
wall defect from three centimetres above up to three centimetres below the umbilicus’. The
size of the hernia is described by the length and width of the hernia (3).
Incisional Hernia
Incidence, prevalence and risk factors
Incisional hernia is the most frequent postoperative complication after abdominal surgery. Approximately 20% of patients undergoing midline laparotomy will develop IH. This can increase to more than 35% in ‘high-risk groups’ (4-12). High-risk groups are defined as patients with an aneurysm of the abdominal aorta (AAA) and obese patients. It is suggested that AAA patients suffer from an underlying connective tissue disorder. A dysregulation of collagen type I/III ratio has an important role in the pathogenesis of distension of the aorta. In the abdominal wall fascia of patients with IH, a reduced type I/III collagen ratio is observed. Patients with a BMI of more or equal than 27 kg/m² have more than 30% chance of developing IH after midline laparotomy (13). These patients have a higher intra-abdominal pressure, which can cause a high tension on abdominal sutures and can thus lead to IH. Besides a high intra-abdominal pressure, there is another factor that can contribute to the development of IH. Obesity is associated with impaired wound healing, due to decreased vascularity of the tissue. This leads to a hypoxic wound, with an impaired synthesis of mature collagen, which results into weaker tissue with poor wound healing. Other risk factors for IH include surgical site infection, smoking, malignancy, diabetes, pulmonary disease, steroid use, malnutrition and collagen disorders like Ehlers Danlos and Marfan diseases (14-18).
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Diagnostic tools
IH is a complication, which should be prevented. However, so far this is not possible. Diagnostics and adequate follow up of IH may be underestimated, but are crucial. Approximately 80% to 95% of all IHs occur within three years after initial surgery. Thus, adequate, reliable long-term follow up is essential in providing high-quality care after midline laparotomies. There are several methods of follow up, such as physical examination and radiological examination (ultrasound, CT-scan). Until now, IH is a clinical diagnosis, which can be made by physical examination alone. Radiological examination (i.e., ultrasound or computed tomography) is being applied in case there is uncertainty regarding diagnosis. Earlier performed studies have shown that the sensitivity of physical examination is 77%, compared with computed tomography (CT) (19). Another study by Den Hartog et al. showed that the sensitivity of ultrasound, compared with CT, was 70.8%, the specificity being 100%, the positive predictive value 100% and the negative predictive value 69.6% (20).
Routinely scheduled outpatient visits to monitor or diagnose IH are time consuming, costly and demand devotion of both patient and doctor. Furthermore, it is not always necessary to conduct a three year follow up after abdominal surgery and patients will not attend a physician if symptoms are absent. Another method of follow-up might be the use of questionnaires (21). However, there is little evidence on their reliability. Currently, there is no validated questionnaire that can be used as a diagnostic tool. Treatment and prevention
Incisional hernia often causes morbidity, such as pain (in patients with symptomatic IH). Furthermore, it can have a negative effect on patients’ quality of life and body image (22-24). Worst-case scenario, it can lead to obstruction or strangulation of the bowel, with possible mortality as a result. Therefore, IH repair is a frequently performed surgical procedure. Studies have shown that mesh reinforcement has a 10-year cumulative recurrence rate of 23%, compared to 63% for primary suture repair (25, 26). The use of mesh in ventral hernia repair is therefore a well-accepted and frequently performed technique. However, the ideal location of mesh placement is still a topic of discussion. Mesh repair can be achieved by placing the mesh intraperitoneally (IPOM), onlay, sublay (retromuscular) or inlay. Currently, there is no level 1-evidence that favours one of these techniques. Focus should be on prevention of IH, specifically in high-risk groups. Nowadays conventional laparotomy can frequently be avoided by performing laparoscopy or horizontal incisions (27). However, this is not always possible. No golden standard is described in literature to prevent IH in patients undergoing midline laparotomy. Prevention can be achieved by mesh reinforcement (either onlay or sublay) in patients, undergoing midline laparotomy. Patients with a high BMI and
patients with AAA might benefit most from prevention. Several prospective studies and randomized controlled trials have already been conducted, investigating how IH can be prevented (8, 10, 28-30), and which surgical technique should be applied in order to lower the incidence of IH. Until recently, there was no level 1-evidence available. The European Hernia Society guidelines on the closure of abdominal wall incisions made a recommendation in 2015. The Guidelines Development Group stated that prophylactic mesh augmentation for an elective midline laparotomy in a high-risk patient is suggested, in order to reduce the IH incidence. However, the evidence was weak and the authors therefore stated as well that larger trials would be needed to make a strong recommendation (2).
The use of meshes
As stated earlier, use of mesh is proven to be beneficial in ventral hernia repair and has become standard practice. The 10-year cumulative recurrence rate of mesh repair of IH has been proven to be 23% (25). This percentage rate is 1% for umbilical hernia repair (31, 32). One of the most important questions that still remain unanswered is: which mesh is the ‘ideal’ mesh? This search is still ongoing, and will not be answered in this thesis. Currently, there are a wide variety of synthetic, biological and biosynthetic, resorbable/ non-resorbable meshes on the market. Several factors determine which mesh is perfect for each specific patient: type of hernia, patient risk factors, type of surgery (clean or contaminated setting) and the indication (prevention or treatment). The most commonly used mesh in ventral hernia repair (in a clean setting) is the non-resorbable synthetic mesh, mostly polypropylene and polyester. These meshes are biocompatible, strong, and inexpensive. However, if placed in contact with abdominal viscera, complications of adhesion formation, small bowel obstruction, pain and enterocutaneous fistulas can occur (33-36). Furthermore, synthetic meshes cannot be easily used in contaminated settings. In these cases, biological meshes should be considered as an alternative. These meshes are made of collagen, containing tissues of human or (most often) animal origin (37). Biological meshes can be divided in cross-linked en non cross-linked meshes. Crosslinking is a chemical process that can be performed to increase the strength and to slow down degradation of the mesh. Biological meshes are gradually vascularized and remodelled in the host tissue by degradation of the extracellular matrix. The use of biological meshes has led to a reduction of foreign body and chronic inflammatory response in a contaminated field, since they are more infection resistant than synthetic materials (38-40). Unfortunately, high evidence in long-term data of clinical outcome and complications is lacking. Another disadvantage is the fact that biological meshes are expensive (37).
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An alternative for abdominal wall repair and soft tissue reinforcement might be the use of slowly resorbable synthetic mesh (‘biosynthetic’ mesh). This mesh aims to combine advantages of both synthetic (no degradation shortly after implantation) and biological (remodelling aspects) meshes. It is also less expensive than a biological mesh. Many studies regarding biosynthetic meshes report that there is ‘optimal tissue remodelling’. However, the definition of this is unclear, not standardized, and furthermore, there is not enough evidence yet that these meshes provide sufficient strength on long-term (41).
Umbilical Hernia
Approximately 10% of all abdominal wall hernias are umbilical hernias. According to the European Hernia Society, an umbilical hernia (UH) is defined as a midline abdominal wall defect from three centimetres above up to three centimetres below the umbilicus. It can either be present at birth, or it can develop spontaneously throughout life, for example by increased intra-abdominal pressure. The prevalence in the adult population is 2%. Each year, approximately 4500 umbilical hernias are repaired in the Netherlands. Surgical repair of umbilical hernia can be performed by either suture or mesh repair. High recurrence rates are reported for suture repair, especially with hernia orifices larger than four centimetres. The recurrence rate for mesh repair is very low, with a percentage of up to one percent (31) (32). At this moment, level-1 evidence is lacking regarding the umbilical hernia size that should be treated with a mesh. The HUMP trial aims to investigate whether mesh repair is superior compared to suture repair in reducing the recurrence rate for smaller umbilical hernias (1-4 centimetres). As expected, the results of the HUMP trial will be published this year.
Most of the UHs are repaired under general anesthesia. Nowadays it is becoming more common to operate patients with inguinal and UHs under local anesthesia. Many studies, investigating local anesthesia for inguinal hernia repair, have been conducted until now. It has been shown that local anesthesia is superior for open inguinal hernia repair, compared to general or spinal anesthesia (42). Local anesthesia can have several advantages, such as less postoperative pain, less micturition problems and early mobilisation of patients, which can lead to a shorter duration of hospital stay. Until now, there is a lack of evidence regarding local anesthesia for the repair of umbilical hernia. A systematic review could not sufficiently show the advantages of local anesthesia, due to the heterogeneity amongst included studies. A prospective cohort study, using Ropivacaine as a local agent and Remifentanil as a sedative, showed that the use of local anesthesia is safe and feasible in umbilical hernia repair.
OUTLINE OF THIS THESIS
The first aim of this thesis is the prevention of incisional hernia. The second aim focuses on new tools, techniques and meshes in ventral hernia surgery.
Part I: Prevention of incisional hernia
Chapter 2 presents the European Hernia Society Guidelines on the closure of abdominal wall incisions. In this study, a recommendation is made regarding prophylactic mesh augmentation in elective midline laparotomies in high-risk patients.
In Chapter 3, the short-term results of the PRIMA trial are presented. This is a randomized controlled trial, investigating the efficacy of mesh reinforcement in high-risk patients undergoing midline laparotomy, in order to reduce the incidence of incisional hernia. The short-term results focus only on the complications in the first month.
Chapter 4 presents the long-term results of the PRIMA trial. In this chapter, it is investigated whether mesh reinforcement is able to prevent incisional hernia in high-risk patients undergoing midline laparotomy.
Chapter 5 presents a meta-analysis of studies describing the results of primary suture versus mesh reinforcement after midline laparotomy. In this meta-analysis it is investigated whether mesh reinforcement reduces the incidence of incisional hernia. Chapter 6 presents a meta-analysis of studies describing the results of primary suture versus mesh reinforcement after midline laparotomy, using a biological or (slow) resorbable synthetic mesh.
Part II: New tools, techniques and meshes in ventral hernia surgery
Chapter 7 presents the PROMID pilot study. In this pilot study, the reliability of a questionnaire, to assist in diagnosing incisional hernia, is being determined.
Chapter 8 is a review, in which an overview is given of the characteristics of slowly resorbable synthetic meshes, for the treatment and prevention of abdominal wall hernias.
Chapter 9 presents the protocol of a prospective cohort study, in which 85 patients with a Ventral Hernia Working Group (VHWG) Grade 3 hernia will be treated with Phasix™ mesh (a slowly resorbable synthetic mesh).
1
Chapter 10 presents the in-vivo characteristics of both synthetic and biological meshesin a validated peritonitis rat model.
Chapter 11 presents a review on the feasibility of local anesthesia for the surgical treatment of umbilical hernia.
Chapter 12 presents a pilot study, in which the safety and feasibility of local anesthesia in the treatment of umbilical hernia is being investigated.
In Chapter 13 the findings of this thesis will be discussed. Furthermore, recommendation for the future will be provided.
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PA R T 1
K. Bury G. Campanelli J. Conze D. Cuccurullo A.C. de Beaux E.B. Deerenberg B. East R.H. Fortelny J.F. Gillion N.A. Henriksen L. Israelsson A. Jairam A. Jänes J. Jeekel M. López-Cano M. Miserez S. Morales-Conde D.L. Sanders M.P. Simons M. Śmietański L. Venclauskas
F. Berrevoet; European Hernia Society
C H A P T E R
2
European Hernia Society Guidelines on
Closure of Abdominal Wall Incisions
ABSTRACT
Background: The material and the surgical technique used to close an abdominal wall incision are important determinants of the risk of developing an incisional hernia. Optimizing closure of abdominal wall incisions holds a potential to prevent patients suffering from incisional hernias and for important costs savings in health care.
Methods: The European Hernia Society formed a Guidelines Development Group to provide guidelines for all surgical specialists who perform abdominal incisions in adult patients on the materials and methods used to close the abdominal wall. The guidelines were developed using the GRADE approach (Grading of Recommendations Assessment, Development and Evaluation) and methodological guidance was taken from SIGN (Scottish Intercollegiate Guidelines Network). The literature search included publications up to April 2014. The guidelines were written using the AGREE II instrument. An update of these guidelines is planned for 2017.
Results: For many of the Key Questions that were studied no high quality data was detected. Therefore, some strong recommendations could be made but, for many Key Questions only weak recommendations or no recommendations could be made due to lack of sufficient evidence.
Recommendations: To decrease the incidence of incisional hernias it is strongly recommended to utilise a non-midline approach to a laparotomy whenever possible. For elective midline incisions, it is strongly recommended to perform a continuous suturing technique and to avoid the use of rapidly absorbable sutures. It is suggested using a slowly absorbable monofilament suture in a single layer aponeurotic closure technique without separate closure of the peritoneum. A small bites technique with a suture to wound length (SL/WL) ratio at least 4/1 is the current preferred method of fascial closure. Currently, no recommendations can be given on the optimal technique to close emergency laparotomy incisions. Prophylactic mesh augmentation appears effective and safe and can be suggested in high-risk patients. For laparoscopic surgery it is suggested using the smallest trocar size adequate for the procedure and closure of the fascial defect if trocars larger or equal to 10 mm are used. For single incision laparoscopic surgery we suggest meticulous closure of the fascial incision to avoid an increased risk of incisional hernias.
2
INTRODUCTION
Background
Incisional hernias are a frequent complication of abdominal wall incisions, but a wide range of incisional hernia rates are reported (1-6). The weighted mean incisional hernia rate at 23.8 months was 12.8 % in a systematic review and meta-regression study(7), but incidence rates up to 69 % have been reported in high-risk patients with prospective long-term follow-up(8). The reported incidence is determined by several factors: the patient population studied, the type of abdominal wall incision, the length of follow-up and the method of incisional hernia diagnosis. Risk factors for incisional hernias include postoperative surgical site infection, obesity and abdominal aortic aneurysm(9-11). Nevertheless, it seems that the suture material and the surgical technique used to close an abdominal wall incision, are the most important determinants of the risk of developing an incisional hernia(4, 12). The development of an incisional hernia has an important impact on the patients’ quality of life and body image(13). Furthermore, the repair of incisional hernias still has a high failure rate with long term recurrence rates above 30%, even when mesh repair is performed(14-16). Optimising the surgical technique to close abdominal wall incisions using evidence based principles, holds a potential to prevent patients suffering from incisional hernias and the potential sequelae of incisional hernia repairs(17). The mean direct and indirect costs for the repair of an average incisional hernia in an average patient in France in 2011 was € 7,089(18). Thus, reducing the incisional hernia rate by optimising the closure of abdominal wall incisions holds a great potential for costs savings in the use of health care facilities and in reducing postoperative disability.
The European Hernia Society (EHS) originated from the “Groupe de la recherche de la paroi abdominal” (GREPA), which was founded in 1979 with the aim: “The promotion of abdominal wall surgery, the study of anatomic, physiologic and therapeutic problems related to the pathology of the abdominal wall, the creation of associated groups which will promote research and teaching in this field, and the development of interdisciplinary relations”. During the autumn board meeting of the EHS in September 2013 in Italy it was decided to extend our mission to actively promote the prevention of incisional hernias by the Sperlonga statement: “Maybe we should first learn and teach how to prevent incisional hernias, rather than how to treat them?”
Objective
The objective is to provide guidelines for all surgical specialists who perform abdominal incisions in adult patients on the optimal materials and methods used to close the abdominal wall. The goal is to decrease the occurrence of both burst abdomen and incisional hernia. The guidelines refer to patients undergoing any kind of abdominal wall incision, including visceral surgery, gynaecological surgery, aortic vascular surgery, urological surgery or orthopaedic surgery. Both open and laparoscopic surgeries are included in these guidelines.
METHODS
As EHS secretary of Quality, Filip Muysoms, under the auspices of the European Hernia Society board, proposed the Guidelines Development Group. The project was presented to the EHS board and accepted during the board meeting in Sperlonga, Italy, on September 28th 2013. The members of the Guidelines Development Group were chosen to recruit key opinion leaders and researchers on the subject from Europe. A geographical distribution across European countries was attempted and some younger surgeons having performed research on the subject were included in the Guidelines Development Group. Many of the members have contributed previously in producing guidelines on a national and international level. The Guidelines Development Group included abdominal wall surgeons, upper gastro-intestinal surgeons, hepato-biliary surgeons, colorectal surgeons and a vascular surgeon.
During a Kick Off meeting of the Guidelines Development Group in the Bonham Hotel in Edinburgh on October 28th 2013, the members attended a seminar on the methodological aspect of developing guidelines by Robin T Harbour, the Lead Methodologist of the Scottish Intercollegiate Guidelines Network (SIGN)(19). The AGREE II instrument was used from the start of the project to guide our methodology and structure of producing the guidelines(20). AGREE II gives as definition for the Quality of a guideline: “The confidence that the potential biases of guideline development have been addressed adequately and that the recommendations are both internally and externally valid, and are feasible for practice.” During this first meeting Key Questions were formulated and translated into 24 patients-intervention-comparison-outcome (PICO) formats. For each Key Question at least three Guidelines Development Group members were assigned as investigators and specific search terms were formulated.
2
On November 11th 2013, a meeting in Glasgow at the SIGN headquarters was held with the steering committee of the Guidelines Development Group to discuss the search strategy. A clinical librarian working for SIGN performed the primary literature research for all Key Questions. This involved a search for systematic reviews and/or meta-analyses on the Key Questions in Medline, Embase, NIHR CRD, NICE and The Cochrane library. The PRISMA flow diagram is shown in Figure1. The Guidelines Development Group members evaluated the systematic reviews for their relevance to the Key Questions and a qualitative assessment was done using the SIGN checklist No 1 for systematic reviews and meta-analyses(19). Only systematic reviews of High Quality were used as basis for the guidelines development. A second search (no filters) on the Key Questions was performed for relevant RCT’s published after the end of the search performed for the systematic reviews involved. If no High Quality systematic review was identified for a Key Question, the working group members performed a separate systematic review using the PRISMA statement methodology(21). To avoid lengthening of this guidelines manuscript, the results of these systematic reviews will be submitted as a separate manuscript on behalf of “The Bonham Group”, which are the members of the Guidelines Development Group. The members working together on a Key Question provided a Summary of Findings table from the results of the literature search, which were presented and discussed during the second group meeting.
The second Guidelines Development Group meeting was held in Edinburgh on April 25th 2014. For evaluation of evidence, the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used(22). For each Key Question, a level of evidence was proposed using the GRADE approach and four levels of quality of the body of evidence were used: high, moderate, low, very low (Table 1). Based on the research evidence, the clinical experience and patient values the Guidelines Development Group formulated a recommendation for each Key Question. In the GRADE approach only three levels of recommendation are used: strong recommendation, weak recommendation and no recommendation.
The results of the guidelines proposed by the Guidelines Development Group were presented during the 36th Annual International Congress of the European Hernia Society in Edinburgh on May 31st 2014. The manuscript was subsequently written by the first author in a uniform manner for all Key Questions and send for review and agreement by all co-authors. Prior to submission, the manuscript of the guidelines was externally reviewed by experts and evaluated using the AGREE II instrument.
Table 1. Using the GRADE approach to guideline development(22) the Quality of the body
of evidence is rated (high/moderate/low/very low) and the recommendations are graded as strong or weak
Grading the Quality of the body of evidence for each Key Questions using the GRADE approach Underlying methodology Quality rating Symbols Definitions
Randomized trials; or double-upgraded observational studies.
High ■■■■ Further research is very unlikely
to change our confidence in the estimate of effect
Downgraded randomized trials; or upgraded observational studies.
Moderate ■■■□ Further research is likely to have
an important impact on our confidence in the estimate of effect and may change the estimate Double-downgraded
randomized trials; or observational studies.
Low ■■□□ Further research is very likely to
have an important impact on our confidence in the estimate of effect and is likely to change the estimate Triple-downgraded randomized
trials; or downgraded observational studies; or case series/case reports.
Very low ■□□□ Any estimate of effect is very
uncertain.
Grading of recommendations using the GRADE approach
Strong recommendation Based on the available evidence, if clinicians are very certain that
benefits do, or do not, outweigh risks and burdens they will make a strong recommendation.
Weak recommendation Based on the available evidence, if clinicians believe that benefits and
risks and burdens are finely balanced, or appreciable uncertainty exists about the magnitude of benefits and risks, they must offer a weak recommendation.
No recommendation If based on the literature research no evidence could be found, no
recommendation can be made.
RESULTS
The results of the searches are shown in the PRISMA flow diagram in Figure 1. From the 97 records detected by the SIGN process, 69 records were excluded based on the title and abstract as not being relevant to the guidelines. The remaining 28 systematic reviews(4, 23-49) were assessed by full text for their relevance to the Key Questions and if retained were assessed qualitatively using the SIGN checklist No 1(19). Additional searches on PubMed and by checking the references of all manuscripts were performed by the members of the Guidelines Development Group assigned to each Key Question. Relevant studies published up until April 2014 were included to provide the Summary of Evidence tables.
2
SIGN process:
Records iden+fied through database searching
n=2819 iden+fied through other sources n=0 Addi+onal records
Records a;er duplicates removed n=2003 (816 removed) Records screened n=97 Economic = 6 Incidence = 7 Socio-‐economic = 2 KQ A = 0 KQ b = 35 KQ C-‐K = 15 KQ L = 7 KQ M = 16 KQ Q-‐P = 0 KQ Q-‐T = 12 KQ U-‐X = 42 Records excluded n=1906
European Hernia Society process:
Records screened by +tle and abstract
for eligibility =97 -‐ Not relevant for our guidelines Records excluded = 69
Studies included in qualita+ve synthesis = 28
Full text ar+cles excluded = 20 -‐ Not relevant for our guidelines -‐ Low quality
Studies included in quan+ta+ve synthesis = 8
References: [1,23,24,26,27,33,43,48]
Figure 1. PRISMA flow diagram for the search for systematic reviews and/or meta-analyses
performed by Scottish Intercollegiate Guidelines Network (SIGN) for the Guidelines Development Group of the European Hernia Society guidelines on the closure of abdominal wall incisions. The search was performed in November 2013 and included searches in Medline, Embase, NIHR CRD, NICE and The Cochrane library
Which diagnostic modality is the most suitable to detect incisional hernias?
No systematic reviews on diagnostic modalities for incisional hernias were found. Fifteen records were included in the qualitative analysis(1-3, 6, 50-60). Only four studies were retained as High Quality and are listed in the Summary of Findings table (Table 2) (3, 50, 51, 60).
The quality of most studies investigating the diagnostic accuracy of imaging techniques was low to very low. Only some provided a sensitivity analysis. Because no studies compared different diagnostic modalities in a similar methodology and with similar study arms, no pooling of data was useful or possible. In general, most studies show that medical imaging will increase the rate of detection of incisional hernias compared to physical examination. In an everyday clinical setting this is usually not important, because most asymptomatic hernias do not require treatment and their diagnosis is thus not necessary.
CT scan is reliable and reproducible, whereas ultrasound is more operator-dependant. However, CT scan will induce a radiation load to the patients and ultrasound is more accessible in most health care settings. A good standardisation and dynamic evaluation by ultrasound of the abdominal wall is needed, as described by Beck et al.(51) as the dynamic abdominal sonography for hernia (DASH) technique.
The difference in accuracy between physical examination and imaging technique is most important in the context of comparative studies evaluating incisional hernia rate. Next to the method of incisional hernia diagnosis the length of follow-up is important. Fink et al.(5) reported in a follow-up study of two prospective trials an increase from 12.6 % at 12 months to 22.4 % at 36 months (p < 0.001) and concluded that follow-up for 3 years should be mandatory in any study evaluating the rate of postoperative incisional hernia after midline laparotomy.
Statement
It is recommended that prospective studies with incisional hernia as a primary outcome integrate medical imaging, either dynamic
ultrasound or CT-scan, in the follow-up. ■■□□
strong
Statement
It is recommended that studies with incisional hernia as a primary outcome include follow-up of at least 24 months (and preferably 36
months). ■■□□
2
Table 2. Summar y of F indings table f or Key Question A: which diag
nostic modalit
y is the most suitable t
o det ec t incisional her nias? Biblio gr aphic cita tion Study t yp e SIGN assessmen t Numb er of pa tien ts Pa tien t char ac teristics In ter ven tion Comparison Length of follo w -up O ut come measur e Bauc om et al . Jour nal of the A mer ican C ollege of Sur geons 2013; 218(3):363-6. pr ospec tiv e cohor t study H igh Q ualit y ++ 181 pa tien ts seen a t a gener al sur ger y depar tmen t who had a pr
ior abdominal oper
ation and
an a
vailable C
T scan within six
mon ths bef or e the visit Ph ysical examina tion by a sur geon C T scan review ed b y sur geon not av ailable Ph ysical e xamina tion had a lo w sensitivit y (77%) and nega tiv e pr edic tiv e v alue (77%). I t fails t o det ec t 23% of her
nias and in 32% of the pa
tien ts with a BMI ≥ 30 kg/m 2. G ener al c ommen ts: Adequa te desig ned study t o c ompar e ph ysical e xamina tion t o C T scan diag
nosis of incisional her
nias . C T scan w as used a " gold standar d" f or the sensitivit y analy sis . Beck et al . Jour nal of the A mer ican C ollege of Sur geons 2013;216(3):447-53 pr ospec tiv e cohor t study H igh Q ualit y ++ 181 pa tien ts seen a t a gener al sur ger y depar tmen t who had a pr
ior abdominal oper
ation and
an a
vailable C
T scan within six
mon ths bef or e the visit dynamic abdominal ultr asound b y sur geon C T scan review ed b y sur geon not av ailable D ynamic Ultr
asound has a high sensitivit
y (98%) and specificit y (88%). I t has a positiv e pr edic tiv e
value of 91 % and nega
tiv e pr edic tiv e v alue of 97%. I t is a good alt er na tiv e t o C T scan diag nosis . G ener al c ommen ts: P aper fr om the same g roup as Bauc om et al . C onc er ns the same pa tien t popula tion. A dequa te desig ned study t o c ompar e dynamic ultr asound t o C T scan diag
nosis of incisional her
nias . C T scan w as used a " gold standar d" f or the sensitivit y analy sis . den Har tog et al . Her nia 2009;13(1):45-8 pr ospec tiv e cohor t study H igh Q ualit y ++ 40 pa tien ts tha t had aor tic sur ger y b y midline incision a t least 12 mon ths bef or e Ultr asound b y radiolog ist C T scan (b y 2 independen t radiolog ists . mean 3.4 years Incisional her nia pr ev alenc e w as 60.0% with C T
scan and 42.5% with ultr
asound
. T
he sensitivit
y of
US w
as 70.8% and the specificit
y 100%. U s has a positiv e pr edic tiv e v
alue of 100% and a nega
tiv e pr edic tiv e v alue of 69.6%. C T scan diag
nosis of the incisional her
nias has a good in tr a- and in ter -obser ver r eliabilit y. G ener al c ommen ts: A dequa te desig ned study t o c ompar e ultr asound t o C T scan diag
nosis of incisional her
nias . No c ompar ison t o ph ysical e xamina tion. Limit ed number of pa tien ts . C T scan w as used as " gold standar d" f or the sensitivit y analy sis . Schr einemacher et al . A rch Sur g. 2011;146:94-9 retr ospec tiv e cohor t study with pr ospec tiv e examina tion H igh Q ualit y ++ 111 pa tien ts tha t ha ve a closur e of a tempor ar y st oma (42% ileost omies and 58% c olost omies). Ultr asound of the abdominal w all b y sur geon Ph ysical examina tion by sur geon median 35 mon ths Incisional her nia pr ev alenc e w as 32.4% with ultr asound ev alua tion. Ph ysical e xamina
tion had a sensitivit
y of 58.3% and a specificit y of 97.3%. The positiv e pr edic tiv e value w
as 91.3% and the nega
tiv e pr edic tiv e value w as 83%. G ener al c ommen ts: B oth e xamina tions w er e per for med b
y the same person. Ultr
asound w as used a " gold standar d" f or the sensitivit y analy sis .
Does the type of abdominal wall incision influence the incidence of incisional hernias or burst abdomen?
Laparotomy incisions can be classified as midline, transverse, oblique or paramedian incisions(61). Six systematic reviews have compared midline laparotomies to alternative incisions(26, 27, 31, 36, 38, 61), but only two were considered High Quality (26, 27). A recent systematic review by Bickenback et al.(26) compared midline, transverse (including oblique) and paramedian incisions. This review included all relevant studies from previous reviews and no additional RCT’s were detected that were published after this review. The literature search of this systematic review(26) identified studies published until 2009 and 24 RCT’s directly comparing different laparotomy incisions were included in the analysis. The incisional hernia rates after non-midline incisions were significantly lower compared to the incisional hernia rates after midline incisions, for both transverse incisions (RR = 1.77; 95 % CI:1.09–2.87) and paramedian incisions (RR = 3.41; 95 % CI: 1.02–11.45)(26). However, data on burst abdomen (deep wound dehiscence or fascial dehiscence) were not significantly different between the different incisions types.
A Cochrane review by Brown et al.(27) published in 2005 and updated in 2011, compared transverse versus midline incisions, but excluded studies comparing paramedian incisions. A decreased incisional hernia rate after transverse incisions was reported compared to midline incisions (OR = 0.49; 95 % CI: 0.30–0.79).
Both reviews concluded that non-midline incisions significantly reduced the risk of incisional hernia compared to midline incisions, but did not influence the risk of burst abdomen. Interestingly, the Cochrane conclusions were more moderate, due to methodological and clinical heterogeneity of the studies and the risk of potential bias.
Statement Non-midline incisions are recommended where possible ■■■□ strong
What is the optimal technique to close a laparotomy incision?
Ten systematic reviews on the techniques and/or the materials to close abdominal wall incisions were identified (4, 32, 34, 37, 38, 42, 43, 48, 62, 63). The data from the different systematic reviews are very incoherent and conclusions are often completely contradictory. The overall quality of most systematic reviews is low and therefore, several should be rejected as evidence to create guidelines. A major problem to identify the evidence from the literature is the fact that most prospective studies compared
2
several variables between the study arms. Moreover, the populations studied are often very different: midline only or including other incisions, emergency or elective surgery, and different operative indications.
The current guidelines on techniques and materials are based on the systematic reviews by Diener et al.(4) and van’t Riet et al.(48) which were evaluated as High Quality. Both systematic reviews included only studies involving midline laparotomies and the review by Diener et al. was the only one to distinguish between elective or emergency surgery. The systematic review by Sajid et al.(43) was used for the question on suture materials and a recent Cochrane review by Gurusamy et al.(62) was used for the question on peritoneal closure.
Using separate PICO’s the shortcoming of many study designs to deliver clear answers becomes obvious. Another shortcoming in most studies on closure of laparotomies is the failure to monitor the technical details of the suturing technique, like the SL/WL ratio and the stitch size. As demonstrated by Israelsson(64) this might be an important confounding factor in studies comparing different suture materials. An updated systematic review taking into account the mentioned shortcomings of individual studies might be performed, but for these guidelines the conclusions are based on the data from the currently available systematic reviews. The protocol for an ongoing Cochrane review(65) was published in 2006 but the final data have not yet been published.
Statement
It is recommended that prospective randomized studies on the suture material to close abdominal wall incisions use the same suturing technique in both study groups.
strong
Statement
It is recommended that prospective randomized studies assessing the technique to close abdominal wall incisions use the same suture material in both study groups.
strong
Continuous suturing versus interrupted sutures
Both meta-analyses concluded that continuous suturing for closure of midline laparotomies was beneficial compared to interrupted closure (4, 48). Diener et al.(4) found a significant lower incisional hernia rate for continuous suturing (OR 0.59: p = 0.001) in elective surgery. Most of the included studies were at high risk of bias because the interrupted study arm used rapidly absorbable multifilament sutures and the continuous arm used either non-absorbable or slowly absorbable monofilament
sutures. van’t Riet et al.(48) included studies involving emergency laparotomies and did not find any difference in incisional hernia rate between interrupted and continuous suturing. Continuous suturing was recommended because it was significantly faster.
Statement Continuous suturing for closure of midline abdominal wall incisions in
elective surgery is recommended ■■□□ strong
Closure versus non-closure of the peritoneum
The Cochrane review by Gurusamy et al.(62) concluded that there was no short-term or long-short-term benefit in peritoneal closure. Five studies were included but were heterogeneous in type of incision (midline and non-midline) and included both elective and emergency laparotomies. In all studies the peritoneum was closed as a separate layer in the study arm with peritoneal closure.
Statement Closure of the peritoneum as a separate layer during closure of laparotomy incisions is NOT recommended ■■□□ weak
Mass closure versus single layer closure
The search for the most appropriate layers to be sutured when closing a laparotomy is hampered by the lack of good definitions on what constitutes a mass closure, layered closure or single layer closure. No clinical studies directly comparing different closure methods were found.
For future research the Guidelines Development Group proposes the following definitions:
• mass closure: the incision is closed with a suture bite including all layers of the
abdominal wall except the skin.
• layered closure: the incision is closed with more than one separate layer of fascial
closure
• single layer aponeurotic closure: the incision is closed by suturing only the abdominal
fascia in one layer.
2
Suture length to wound length ratio (SL/WL)
The beneficial effect of a high SL/WL ratio on reducing the incidence of incisional hernias has been recognised for a long time(66), but evidence from clinical prospective studies remains scarce and most of the work addressing the topic comes from the Clinic of Sundsvall in Sweden(64, 67, 68). A RCT, performed in Sundsvall, demonstrated the importance of the SL/WL ratio in reducing incisional hernia rate. The critical value was determined to be at a ratio of 4/1(64). Although a SL/WL ratio ≥4 is often mentioned in the protocol of prospective studies, many fail to document that the SL/WL ratio was recorded for the individual study patients.
Statement
A suture to wound length ratio (SL/WL) of at least 4/1 for continuous closure of midline abdominal wall incisions in elective surgery is
suggested. ■■□□
weak
Statement
It is recommended that all prospective studies on the closure of laparotomy incisions will document the suture to wound length ratio (SL/WL) in all patients, as well as the number of stitches.
strong
Small bites versus large bites
Millbourn et al.(69) demonstrated that closure of a midline laparotomy with a "small bites" technique resulted in significant less incisional hernias (5.6% vs 18.0 %; p< 0.001) and less surgical site infections (SSIs) (5.2% vs 10.2%; p= 0.02). In the small bite technique the laparotomy wound is closed with a single layer aponeurotic suturing technique taking bites of fascia of 5 - 8 mm and placing stitches every 5 mm.
Statement The "small bites technique" for continuous closure of midline incisions
is suggested. ■■■□ weak
What is the optimal suture material to close a laparotomy incision?
Despite significant heterogeneity and confounders in most SRs identified, a study by Sajid et al.(43) focused solely on the suture material. Table 3 defines the suture materials used in the included studies.
Rapidly absorbable suture versus non-absorbable or slowly absorbable sutures
Diener et al. (4) reported a significantly lower incisional hernia rate with slowly absorbable sutures (OR 0.65: p= 0.009) in elective surgery. Subgroup analysis performed by van 't Riet et al.(48) comparing only continuous suturing studies, detected only one
RCT by Wissing et al.(70) using continuous suturing in both study arms. This study, which included 21% of emergency operations, showed significantly more incisional hernias with rapidly absorbable sutures compared to non-absorbable sutures (p= 0.001) and compared to slowly absorbable sutures (p = 0.009).
Statement The use of rapidly absorbable suture material for closure of midline
abdominal wall incisions in elective surgery is NOT recommended. ■■■□ strong
Table 3. List of the most commonly used suture materials to close abdominal wall incisions and
their characteristics
Suture Producer Material Absorbable
Absorption
time Filaments
Antibiotics impragnated
Prolene Ethicon Polypropylene Non Mono No Surgipro Covidien Polypropylene Non Mono No
Ethilon Ethicon Nylon Non Mono No
Monosof Covidien Nylon Non Mono No
Ethibond Ethicon Polyethylene Non Multi No Mersilene Ethicon Polyester Non Multi No Surgilon Covidien Nylon Non Multi No Maxon Covidien Polyglyconate Slowly 180 days Mono No PDS Ethicon Polydioxanone Slowly 183–238 days Mono No PDS plus Ethicon Polydioxanone + triclosan Slowly 183–238 days Mono Yes Monoplus B Braun Polydioxanone Slowly 180–201 days Mono No Monomax B Braun Poly-4-hydroxybutyrate Slowly 390–1080 days Mono No Vicryl Ethicon Polyglactin Rapidly 56–70 days Multi No Vicryl plus Ethicon Polyglactin + triclosan Rapidly 56–70 days Multi Yes Polysorb Covidien Polyglycolic acid Rapidly 60–90 days Multi No Dexon Covidien Polygglycolic acid Rapidly 60–90 days Multi No
Non-absorbable versus slowly absorbable sutures
No difference in incisional hernia rate for continuous suturing of midline incisions with slowly absorbable versus non-absorbable sutures (p= 0.75) was identified(48). However, an increased incidence of prolonged wound pain (p< 0.005) and suture sinus formation (p= 0.02) with non-absorbable sutures was reported(48). Another MA (which included non-midline incisions) identified no difference in incisional hernia rate between
slowly-2
absorbable polydioxanone and non-absorbable sutures (OR 1.10: p= 0.43)(43). Once again, non-absorbable sutures had a significant higher risk of suture sinus formation (OR 0.49: p= 0.01)(43).
Statement
Using slowly-absorbable suture material instead of non-absorbable sutures for continuous closure of midline abdominal wall incisions in
elective surgery is suggested. ■■□□
weak
Monofilament versus multifilament sutures
Monofilament sutures are believed to be associated with a lower SSI rate than multifilament sutures(12). However, none of the SRs commented on this issue specifically. If the previous recommendation to use slowly absorbable sutures for closure of elective midline laparotomies is followed, this question becomes superfluous because the slowly absorbable sutures are all monofilament sutures.
Statement We suggest using monofilament suture material for continuous closure of midline abdominal wall incisions in elective surgery. ■□□□ weak
Concerning the size of the suture, no studies comparing directly the size of the sutures used to close abdominal wall incisions were identified during our searches. For the "small bites" technique, Isrealsson et al(12) suggest to use a suture size USP 2/0 (USP = United States Pharmacopeia).
Statement No recommendation on the size of the sutures for closure of abdominal
wall incisions can be given due to lack of data. ■□□□ no
Sutures impregnated with antibiotics
Sutures coated with Triclosan as an antimicrobial agent have been introduced to decrease the rate of surgical site infection in surgery. A recent meta-analysis has demonstrated a significant beneficial effect in the prevention of surgical site infection after all kinds of surgery(71). Surgical site infection is a risk factor for subsequent development of incisional hernias and therefore the use of antibiotics impregnated sutures to close laparotomies might be beneficial in the prevention of incisional hernias. Recently Diener et al.(72) published a large RCT on 1,224 patients undergoing an elective midline laparotomy comparing polydioxanone sutures with versus without triclosan impregnation. No reduction in the incidence of surgical site infection was reported (OR
0.91: CI 0.66–1.25; p = 0.39). Four other RCT’s have compared sutures with or without triclosan in laparotomy closure, either with polyglactin sutures (Vicryl)(73, 74) or with polydioxanone (PDS)(75, 76). A meta-analysis on all five studies performed by Diener et al. showed a significant decrease in surgical site infection (OR 0.67: CI 0.47–0.98). No data on incisional hernias are available from these studies.
Statement
Monofilament sutures impregnated with antibiotics for closure of elective midline incisions is NOT advised, because of insufficient data on their efficiency on prevention of surgical site infections and the lack of data on incisional hernias or burst abdomen.
■■■□ weak
Limitations of the statements in these guidelines on suture technique and suture materials
The statements are limited by the quality of the data on which they are based. In total, 61 RCT's have been identified that compared suture materials or techniques to close laparotomy incisions. Many studies have more than one variable between study arms and therefore analysing them in meta-analyses is difficult. Moreover, many studies have flaws in the methodology increasing the risk of bias. We would like to encourage researchers that plan studies on abdominal wall closure to improve the methodology of their study protocol. Preferably study arms are only different in the variable under investigation, either a suture technique or a suture material. Moreover we recommend documenting the technical details such as SL/WL ratio, the number of stitches used in the patients and to provide a follow up of at least 24 months.
Although some of the systematic reviews detected included non-midline incisions(43) or emergency operations(48), these guidelines are currently limited to elective midline laparotomies. For emergency operations and non-midline incisions there is currently not enough data available.
Statement No recommendation on suture material or suturing technique for use in emergency surgery can be given due to lack of sufficient data. ■□□□ no
Statement No recommendation on suture material or suturing technique for use in
2
Suture needles and retention sutures
Blunt tip versus sharp needles
Only one SR assessing the type of needle used to close the abdominal wall(23) and one RCT comparing blunt needles with sharp needles were identified. The RCT reported no difference in SSI rate between blunt and sharp needles(77).
Statement No recommendation on the type or the size of needle to close a laparotomy can be given due to lack of data. ■□□□ no
Is there a place for retention sutures when closing a laparotomy?
No SR on the use of retention sutures was found. Eight records were screened by full text(78-85). Three RCTs on the prevention of burst abdomen by using either retention sutures or a reinforced tension line suture in patients with increased risk for wound dehiscence and burst abdomen were identified(78, 81, 85). Follow up was too short to evaluate incisional hernia rate. The Summary of Evidence is listed in Table 4. Two studies showed favourable results(78, 81), but one study reported a high number of adverse events when using retention sutures(85).
Statement
No recommendation on the use of retention sutures in patients with multiple risk factors for burst abdomen can be given due to insufficient
data. ■■□□
no
Postoperative care
Postoperative management and instructions for patients are not supported by high quality prospective data, but rely mostly on surgeons' habits, tradition and common beliefs (86-88). Long term follow up studies are needed to research the impact on the occurrence of incisional hernias of prescribing abdominal binders or restricting postoperative activity. The additional searches did not reveal any relevant study on long term outcome. Some studies on the short term benefits of abdominal binders were found.
Table 4. Summar y of F indings table f or Key Q uestion M: is ther e a plac e f or r et en tion sutur
es when closing a lapar
ot om y? Biblio gr aphic cita tion Study typ e Numb er of pa tien ts Pa tien t char ac teristics In ter ven tion Comparison Length of follo w -up O ut come measur e Khor gami et al . J Sur g R es . 2013;180:238-43. RC T 300 Pa tien ts under going midline lapar ot om y with ≥ 2 r isk fac tors of a list of defined r isk fac tors f or burst abdomen ex tr a r et en tion sutur es N ylon 1 (ev er y 10 cm
and with 5 cm bit
es of sk in) kept f or 3-4 w eeks con tinuous loop siz e 1 n ylon sutur e (1 cm fr om the edge /1 cm in ter vals) median 5 mon ths W ound dehisc enc e w as 4.1% (6/147) in the in ter ven tion g roup and 13.5% (20/148) in the c on tr ol g roup (p = 0.007). "We sho w ed tha t pr oph ylac tic ret en tion sutur es c ould r educ e w ound dehisc enc e in midline lapar ot om y in high-r isk pa tien ts with multiple risk fac
tors without imposing
remar kable post oper ativ e complica tions . " Ag ra w al Tr op G astr oen ter ol . 2009;30:237-40. RC T 190 Emer genc y midline lapar ot om y reinf or ced t ension line sutur e con tinuous sutur e Burst abdomen w as 0.0% (0/90) in the in ter ven tion g roup and 13.0% (13/100) in the c on tr ol g roup (p = 0.0026). "Closur e of midline incision b y R TL reduc es the incidenc e of burst abdomen. "
Rink et al Eur J Sur
g. 2000;166:932-7. RC T 95 (92 midline) Pa tien ts needing major abdominal sur ger y with inf ec tiv e or malig nan t in tr a-abdominal diseases . + a t least one r isk fac tor ex tr a r et en tion sutur es with sutur es r et en tion br idge f or 12 da ys in ter rupt ed V icr yl 1 sutur es 12 da ys "R et en tion sutur es used t o close abdominal w ounds cause inc on venienc
e, pain, and specific
mor
bidit
